1. Field of the Invention
The present invention relates to an image output apparatus that can output an image to a printing section and a display section.
2. Description of the Related Arts
Apparatuses that print an image and display the image onto a display section have been known. For example, there are some facsimile apparatuses or digital multi function peripherals provided with a display section which can not only print a received image or read image but also display the image onto the display section. This is related to a situation in which a cheap and high-definition dot matrix display apparatus represented by a liquid crystal display apparatus has been available in recent years. Specifically, a conventional display apparatus incorporated into a device generally has less display dot number and small screen, so that it is unsuitable for displaying an image. However, with the progress of the display apparatus described above, a display apparatus that can also be used for displaying an image has been adopted.
For example, there has been proposed an apparatus that displays, for a preview, an expected print image based on a print condition that is inputted and set, prior to a printing process (refer to Japanese Unexamined Patent Publication No. 2000-062288).
As described above, the most general purpose in displaying an image onto a display section in the apparatus (hereinafter referred to as an image output apparatus in this specification) that can display the image to be printed onto the display section is the preview before the printing. The basis of the preview function is to display the condition corresponding to the finish of the printing onto the display section.
In general, data of an image to be printed is stored as coded or compressed in an image memory in an output apparatus. In order to print or display the stored image data, it is necessary that the image data be read from the image memory so as to decode or expand the data. The image output apparatus includes an image processing section for performing these processes. These processes are needed to print and display the image, and further, reasonable processing time is needed since complicated process is performed for image data having large capacity. When a new processing request for another data is received during these processes, it is general that the processing request received later is registered in a queue so as to be brought into a stand-by state until the processing, which is currently executed, is completed. This is because the image processing section does not have a capability of simultaneously executing the processing request received later without delaying the processing that is currently executed.
Even if the image processing section has a high processing capability, it takes reasonable time for a printing section to print the image. Therefore, a conventional image output apparatus determines the capability of the image processing section so as to be matched with the processing capability (printing speed) of the printing section. This is because, even when the capability of the image processing section is increased more, the printing speed is not increased, although cost is vainly increased.
On the other hand, the processing speed of the display section is generally higher than the processing speed of the printing section. For example, the printing section having a printing speed of 60 sheets/min. (A4 size) prints an image of an A4 size in one second, while the rewriting speed of the display section for one screen is generally much higher than this speed. Therefore, the display speed of the preview image is determined according to the capability of the image processing section, not determined according to the drawing capability of the display section. Therefore, a user who gives an instruction of a preview display has to wait for some time until the preview image is displayed onto a screen after the instruction is given. Since a screen of a television or a personal computer is more rapidly switched than the situation described above, the user is not used to be waited. Even so, it is not realistic that cost is increased only for the preview function, which can be said to be ancillary, in order to enhance the capability of the image processing section. Further, it is not a suitable measure to always carry out the preview process in preference to the printing process. When the request for the preview is frequently made, the printing speed might be reduced apparently.